Connectivity issue on Amtrak

I honestly could not think of a better place to post this (discuss.amtraktrains.com, maybe?), but I've been having occasional connectivity issues on my MacBook Air when I take the Amtrak. Typically, an AmtrakConnect window would pop up asking me if I accept the terms of service, and then let me on. But I've had several occasions (including the last two), where that window doesn't pop up and AmtrakConnect is not listed among the available networks. Any possible theories behind why? I initially thought it only happened when I opened my laptop before the train departs Chicago's terminal, but I've since encountered it on other occasions as well.